diff --git a/riscos/filename.c b/riscos/filename.c
index 7fb0031b7..8ec8ea217 100644
--- a/riscos/filename.c
+++ b/riscos/filename.c
@@ -15,19 +15,20 @@
 #include <string.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include "oslib/osgbpb.h"
 #include "oslib/osfile.h"
 #include "netsurf/riscos/filename.h"
 #include "netsurf/utils/log.h"
 
 #define FULL_WORD (unsigned int)4294967295
 /* '0' + '0' * 10 */
-#define START_PREFIX 528 
+#define START_PREFIX 528
 
 struct directory {
-  	int numeric_prefix;		/** numeric representation of prefix */
+	int numeric_prefix;		/** numeric representation of prefix */
 	char prefix[10];		/** directory prefix, eg '00.11.52.' */
-  	unsigned int low_used;		/** first 32 files, 1 bit per file */
-  	unsigned int high_used;		/** last 32 files, 1 bit per file */
+	unsigned int low_used;		/** first 32 files, 1 bit per file */
+	unsigned int high_used;		/** last 32 files, 1 bit per file */
 	struct directory *next;		/** next directory (sorted by prefix) */
 };
 
@@ -37,7 +38,8 @@ static char ro_filename_buffer[12];
 static char ro_filename_directory[256];
 
 static struct directory *ro_filename_create_directory(const char *prefix);
-
+static bool ro_filename_flush_directory(const char *folder, int depth);
+static bool ro_filename_delete_recursive(char *folder);
 
 /**
  * Request a new, unique, filename.
@@ -47,15 +49,15 @@ static struct directory *ro_filename_create_directory(const char *prefix);
 char *ro_filename_request(void) {
 	struct directory *dir;
 	int i = -1;
-	
+
 	for (dir = root; dir; dir = dir->next)
 		if ((dir->low_used & dir->high_used) != FULL_WORD) {
-		  	if (dir->low_used != FULL_WORD) {
+			if (dir->low_used != FULL_WORD) {
 				for (i = 0; (dir->low_used & (1 << i)); i++);
-		  	} else {
+			} else {
 				for (i = 0; (dir->high_used & (1 << i)); i++);
-		  		i += 32;
-		  	}
+				i += 32;
+			}
 			break;
 		}
 	if (i == -1) {
@@ -86,28 +88,28 @@ bool ro_filename_claim(const char *filename) {
 	char dir_prefix[9];
 	int file;
 	struct directory *dir;
-	
+
 	/* filename format is always '01.23.45.XX' */
 	strncpy(dir_prefix, filename, 9);
 	dir_prefix[9] = '\0';
 	file = (filename[10] + filename[9] * 10 - START_PREFIX);
-	
+
 	/* create the directory */
 	dir = ro_filename_create_directory(dir_prefix);
 	if (!dir)
 		return false;
 
 	/* update the entry */
-  	if (file < 32) {
-  	  	if (dir->low_used & (1 << file))
-  	  		return false;
-  		dir->low_used |= (1 << file);
-  	} else {
-  	  	if (dir->high_used & (1 << (file - 32)))
-  	  		return false;
-  		dir->high_used |= (1 << (file - 32));
-  	}
-  	return true;
+	if (file < 32) {
+		if (dir->low_used & (1 << file))
+			return false;
+		dir->low_used |= (1 << file);
+	} else {
+		if (dir->high_used & (1 << (file - 32)))
+			return false;
+		dir->high_used |= (1 << (file - 32));
+	}
+	return true;
 }
 
 
@@ -125,14 +127,14 @@ void ro_filename_release(const char *filename) {
 		((filename[4] + filename[3] * 10 - START_PREFIX) << 6) |
 		((filename[1] + filename[0] * 10 - START_PREFIX) << 12));
 	file = (filename[10] + filename[9] * 10 - START_PREFIX);
-	
+
 	/* modify the correct directory entry */
 	for (dir = root; dir; dir = dir->next)
 		if (dir->numeric_prefix == index) {
-		  	if (file < 32)
-		  		dir->low_used &= ~(1 << file);
-		  	else
-		  		dir->high_used &= ~(1 << (file - 32));
+			if (file < 32)
+				dir->low_used &= ~(1 << file);
+			else
+				dir->high_used &= ~(1 << (file - 32));
 			return;
 		}
 }
@@ -146,7 +148,6 @@ bool ro_filename_initialise(void) {
 	xosfile_create_dir("<Wimp$ScrapDir>.WWW", 0);
 	xosfile_create_dir("<Wimp$ScrapDir>.WWW.NetSurf", 0);
 	xosfile_create_dir("<Wimp$ScrapDir>.WWW.NetSurf.Cache", 0);
-
 	return true;
 }
 
@@ -155,8 +156,174 @@ bool ro_filename_initialise(void) {
  * Deletes all files in the cache directory that are not accounted for.
  */
 void ro_filename_flush(void) {
-	// todo: delete any files that aren't known of
-	// todo: delete any empty references (?)
+	xhourglass_on();
+	while (ro_filename_flush_directory(CACHE_FILENAME_PREFIX, 0));
+	xhourglass_off();
+}
+
+
+/**
+ * Deletes some files in a directory that are not accounted for.
+ *
+ * A single call to this function may not delete all the files in
+ * a directory. It should be called until it returns false.
+ *
+ * \param folder	the folder to search
+ * \param depth		the folder depth
+ * \returns whether further calls may be needed
+ */
+bool ro_filename_flush_directory(const char *folder, int depth) {
+	bool changed = false;
+	bool del;
+	int number, i;
+	int prefix = 0;
+	unsigned int prefix_mask = (63 << 12);
+	int context = 0;
+	int read_count;
+	osgbpb_INFO(100) info;
+	os_error *error;
+	char child[256];
+	const char *prefix_start = NULL;
+	struct directory *dir = NULL;
+
+	/* find out directory details */
+	if (depth > 0)
+		prefix_start = folder + strlen(folder) - depth * 3 + 1;
+	for (i = 0; ((i < depth) && (i < 3)); i++) {
+	  	number = prefix_start[1] + prefix_start[0] * 10 - START_PREFIX;
+		prefix |= (number << (12 - i * 6));
+		prefix_mask |= (63 << (6 - i * 6));
+		prefix_start += 3;
+	}
+	if (depth == 3) {
+		for (dir = root; dir; dir = dir->next)
+			if (dir->numeric_prefix == prefix)
+				break;
+		if ((!dir) || (dir->numeric_prefix != prefix))
+			return false;
+	}
+
+	while (context != -1) {
+		/* read some directory info */
+		error = xosgbpb_dir_entries_info(folder,
+				(osgbpb_info_list *) &info, 1, context,
+				sizeof(info), 0, &read_count, &context);
+		if (error) {
+			LOG(("xosgbpb_dir_entries_info: 0x%x: %s",
+				error->errnum, error->errmess));
+			if (error->errnum == 0xd6)	/* no such dir */
+				return false;
+			break;
+		}
+		/* ensure we read some data */
+		if (read_count == 0)
+			continue;
+		/* first 3 depths are directories only, then files only */
+		del = false;
+		if (depth < 3) {
+			if (info.obj_type != fileswitch_IS_DIR)
+				del = true;
+		} else {
+			if (info.obj_type != fileswitch_IS_FILE)
+				del = true;
+		}
+		/* check we are a file numbered '00' -> '63' */
+        	if ((!del) && (info.name[0] >= '0') && (info.name[0] <= '6') &&
+				(info.name[1] >= '0') && (info.name[1] <= '9') &&
+				(info.name[2] == '\0')) {
+			number = atoi(info.name);
+			if ((number >= 0) && (number <= 63)) {
+				if (depth == 3) {
+					if (number < 32)
+						del = !(dir->low_used &
+							(1 << number));
+					else
+						del = !(dir->high_used &
+							(1 << (number - 32)));
+				} else {
+				  	del = true;
+					prefix &= ~(63 << (12 - depth * 6));
+					prefix |= (number << (12 - depth * 6));
+					for (dir = root; dir; dir = dir->next) {
+						number = dir->numeric_prefix &
+								prefix_mask;
+						if (number == prefix) {
+							del = false;
+							break;
+						}
+					}
+				}
+			} else {
+				del = true;
+			}
+		} else {
+			del = true;
+		}
+		/* continue if we are a valid reference so far */
+       		if ((!del) && (info.obj_type != fileswitch_IS_DIR))
+			continue;
+		/* delete or recurse */
+		snprintf(child, 256, "%s.%s", folder, info.name);
+		child[255] = '\0';
+		if (del) {
+			if (info.obj_type == fileswitch_IS_DIR)
+				ro_filename_delete_recursive(child);
+			error = xosfile_delete(child, 0, 0, 0, 0, 0);
+			if (error)
+				LOG(("xosfile_delete: 0x%x: %s",
+					error->errnum, error->errmess));
+			else
+				changed = true;
+		} else {
+			while (ro_filename_flush_directory(child, depth + 1));
+		}
+	}
+	return changed;
+}
+
+
+/**
+ * Recursively deletes the contents of a directory
+ *
+ * \param directory	the directory to delete
+ * \return true on success, false otherwise
+ */
+bool ro_filename_delete_recursive(char *folder) {
+	int context = 0;
+	int read_count;
+	osgbpb_INFO(100) info;
+	os_error *error;
+	char child[256];
+
+	while (context != -1) {
+		/* read the first entry */
+		error = xosgbpb_dir_entries_info(folder,
+				(osgbpb_info_list *) &info, 1, 0,
+				sizeof(info), 0, &read_count, &context);
+		if (error) {
+			LOG(("xosgbpb_dir_entries_info: 0x%x: %s",
+				error->errnum, error->errmess));
+			if (error->errnum == 0xd6)	/* no such dir */
+				return false;
+			break;
+		}
+		/* ensure we read some data */
+		if (read_count == 0)
+			continue;
+		snprintf(child, 256, "%s.%s", folder, info.name);
+		/* recurse for files */
+		if (info.obj_type == fileswitch_IS_DIR) {
+		  	if (!ro_filename_delete_recursive(child))
+		  		return false;
+		}
+		error = xosfile_delete(child, 0, 0, 0, 0, 0);
+		if (error) {
+			LOG(("xosfile_delete: 0x%x: %s",
+				error->errnum, error->errmess));
+			return false;
+		}
+  	}
+  	return true;
 }
 
 
@@ -165,7 +332,7 @@ void ro_filename_flush(void) {
  *
  * \param  prefix  the prefix to use, or NULL to allocate a new one
  * \return a new directory structure, or NULL on memory exhaustion
- * 
+ *
  * Empty directories are never deleted, except by an explicit call to
  * ro_filename_flush().
  */
@@ -219,11 +386,11 @@ static struct directory *ro_filename_create_directory(const char *prefix) {
 		new_dir->next = prev_dir->next;
 		prev_dir->next = new_dir;
 	}
-	
+
 	/* if the previous directory has the same parent then we can simply
 	 * create the child. */
 	if ((prev_dir) && (!strncmp(prev_dir->prefix, new_dir->prefix, 6))) {
-	  	new_dir->prefix[8] = '\0';
+		new_dir->prefix[8] = '\0';
 		sprintf(ro_filename_directory, "%s.%s",
 				CACHE_FILENAME_PREFIX, new_dir->prefix);
 		new_dir->prefix[8] = '.';
@@ -236,7 +403,7 @@ static struct directory *ro_filename_create_directory(const char *prefix) {
 		LOG(("xosfile_create_dir: 0x%x: %s",
 				error->errnum, error->errmess));
 	}
-	
+
 	/* create the directory structure */
 	sprintf(ro_filename_directory, "%s.", CACHE_FILENAME_PREFIX);
 	last_1 = ro_filename_directory + strlen(CACHE_FILENAME_PREFIX) + 1;
@@ -245,7 +412,7 @@ static struct directory *ro_filename_create_directory(const char *prefix) {
 		*last_1++ = *last_2++;
 		while (*last_2 && *last_2 != '.')
 			*last_1++ = *last_2++;
-		if (*last_2) {		 	
+		if (*last_2) {
 			last_1[0] = '\0';
 			error = xosfile_create_dir(ro_filename_directory, 0);
 			if (error) {