diff --git a/polkadot/network/src/legacy/collator_pool.rs b/polkadot/network/src/legacy/collator_pool.rs
index 89b7ba3a52..e13b2dc8fd 100644
--- a/polkadot/network/src/legacy/collator_pool.rs
+++ b/polkadot/network/src/legacy/collator_pool.rs
@@ -65,6 +65,7 @@ impl CollationSlot {
 	}
 }
 
+#[derive(Debug)]
 enum SlotEntries {
 	Blank,
 	// not queried yet
@@ -75,7 +76,7 @@ enum SlotEntries {
 
 impl SlotEntries {
 	fn received_collation(&mut self, collation: Collation) {
-		*self = match ::std::mem::replace(self, SlotEntries::Blank) {
+		*self = match std::mem::replace(self, SlotEntries::Blank) {
 			SlotEntries::Blank => SlotEntries::Pending(vec![collation]),
 			SlotEntries::Pending(mut cs) => {
 				cs.push(collation);
@@ -185,6 +186,12 @@ impl CollatorPool {
 	/// The collator should be registered for the parachain of the collation as a precondition of this function.
 	/// The collation should have been checked for integrity of signature before passing to this function.
 	pub fn on_collation(&mut self, collator_id: CollatorId, relay_parent: Hash, collation: Collation) {
+		log::debug!(
+			target: "collator-pool", "On collation from collator {} for relay parent {}",
+			collator_id,
+			relay_parent,
+		);
+
 		if let Some((para_id, _)) = self.collators.get(&collator_id) {
 			debug_assert_eq!(para_id, &collation.info.parachain_index);
 
diff --git a/polkadot/parachain/src/lib.rs b/polkadot/parachain/src/lib.rs
index 3f1993a23e..d3f24c34bf 100644
--- a/polkadot/parachain/src/lib.rs
+++ b/polkadot/parachain/src/lib.rs
@@ -81,9 +81,9 @@ pub struct ValidationResult {
 /// Unique identifier of a parachain.
 #[derive(
 	Clone, CompactAs, Copy, Decode, Default, Encode, Eq,
-	Hash, Ord, PartialEq, PartialOrd, RuntimeDebug
+	Hash, Ord, PartialEq, PartialOrd, RuntimeDebug,
 )]
-#[cfg_attr(feature = "std", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "std", derive(serde::Serialize, serde::Deserialize, derive_more::Display))]
 pub struct Id(u32);
 
 impl TypeId for Id {
diff --git a/polkadot/validation/src/collation.rs b/polkadot/validation/src/collation.rs
index 0be87a5a94..cb60d4b532 100644
--- a/polkadot/validation/src/collation.rs
+++ b/polkadot/validation/src/collation.rs
@@ -614,6 +614,8 @@ pub fn validate_collation<P>(
 {
 	let para_id = collation.info.parachain_index;
 
+	debug!("Validating collation for parachain {} at relay parent: {}", para_id, relay_parent);
+
 	do_validation(
 		client,
 		relay_parent,